1. Center for Sustainable Mobility, Virginia Tech Transportation Institute
2. Charles E. Via, Jr., Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, 3500 Transportation Research Plaza, Blacksburg, VA 24061.
3. Department of Civil Engineering, Chosun University, 309 Pilmun-Daero, Dong-Gu, Gwangju, 501-759, South Korea.